The present invention relates to a valve operating mechanism for an internal combustion engine, including a camshaft rotatable in synchronism with the rotation of the internal combustion engine and having integral cams for operating a pair of intake or exhaust valves, and rocker arms or cam followers angularly movable supported on a rocker shaft for opening and closing the intake or exhaust valves in response to rotation of the cams.
Japanese Laid-Open Patent Publication No. 59(1984)-226216, for example, discloses a valve operating mechanism for use in an internal combustion engine having a plurality of intake or exhaust valves per engine cylinder. Some of the intake or exhaust valves remain closed when the engine operates at a low speed. If the intake or exhaust valves of a particular engine cylinder of a multicylinder internal combustion engine could be kept inoperative in order to cut off the operation of the particular engine cylinder, fuel consumption would be reduced by stopping the operation of the intake or exhaust valves of the particular engine cylinder while the engine operates in a low-speed range. However, no satisfactory devices have been available in the past to achieve such a task.